Hi - I have a 3-story home (basement and two floors above)with 5 toilets (1 in basement, 1 on main floor, 3 on upstairs floor.

The house has a mansard style roof which I just replaced which caused me to notice that I have no vent stacks on the roof for the toilets (there's one vent but I think it is for a fan in an interior shower).

My question is-- if the toilet's don't vent throught the roof -- where else do they vent (the only other known/visible exhausts are on the ground level for the dryer and the ground floor bathroom fan). The builders did some other strange things with the house so I am curious how the toilets (and possible the sinks??) vent. thanks very much